Blackberries (Rubus subgenus Rubus Watson) are a well-known, aggregate fruit generally popular throughout the world. Traditional blackberry plants produce small dark black clusters of fruit once per season on second-year cane growth known as floricanes. The plants are often thorn bearing varieties with various spines along the canes which hinder fruit harvest and plant maintenance. More recent breeding efforts have led to the development of primocane-fruiting blackberries which produce fruit on first year canes (i.e. primocanes) as well as second-year floricanes. Such primocane-fruiting blackberries generally produce fruit in late summer to autumn, whereas floricane-fruiting types commonly bear fruit in early to mid-summer. The additional extended harvest season for primocanes offers fresh market growers a significant economic advantage over more typical floricane-fruiting cultivars.
One example of an existing primocane-fruiting blackberry variety is ‘APF-122’, U.S. Plant Pat. No. 27,401, which has a very firm round small fruit size (5.8 g on average) and a significantly early fruiting season (average ripe fruit date for primocanes on ‘APF-122’ is 5-6 months after planting). ‘Reuben’, U.S. Plant Pat. No. 23,497, is another example of a primocane blackberry, although not generally grown in California. ‘Reuben’ has much larger fruits than ‘APF-122’, averaging 14.5 g versus 5.8 g, respectively. The fruits of ‘Reuben’ are oblong and blocky, while fruits of ‘APF-122’ are round. Also, ‘Reuben’ is a late-fruiting primocane variety, compared to the early fruiting season of ‘APF-122’.
The present invention comprises a new and distinct lightly thorned cultivar of primocane blackberry referred to by the cultivar name ‘MM01’. The new variety, only lightly thorned, was originally identified as selection no. MA10-05, and originated from a cross made by Mario Aguas-Alvarado in a controlled breeding program in Freedom, Calif. USA. ‘MM01’ was initially believed to be fully thorn-less but successive generations have shown a few thorns at the base, less thorns on the midpoint and no thorns at the terminal point of the canes. The male parent of the new variety is variety known as ‘Navaho’, U.S. Plant Pat. No. 6,679 and the female parent is the variety known as ‘APF45’, U.S. Plant Pat. No. 22,449. The new variety ‘MM01’ has been asexually reproduced by vegetative side shoot in Freedom, Calif., and the distinguishing characteristics are retained through successive generations of asexual reproduction.